A definitive answer is not yet known, but theories ranging from algae blooms to Armageddon have begun to surface since the young seals began washing ashore in early September.

Other theories floated from community members over the last few weeks include questions of whether toxins from jelly fish stings, radiation from an unreported release of cooling water from the Seabrook nuclear power plant, or last year's oil spill in the Gulf of Mexico could be to blame.

So far investigators from the New England Aquarium and the National Oceanic and Atmospheric Association have ruled out only a handful of potential reasons for the spike in seal deaths.

The investigation, which began only weeks ago after numerous dead seals were found on various Seacoast beaches, has revealed approximately 94 seal carcasses have washed ashore since Sept. 1.

Mendy Garron, regional marine mammal stranding coordinator for NOAA, said the seals have been found on beaches from southern Maine to the North Shore of Massachusetts. Other animal species, such as whales and a bluefin tuna, have also washed ashore, said Garron, but not at the frequency of the young harbor seals.

Much like everyone else looking into the seal deaths, Garron said she's not sure what the cause is just yet.

"When we see numbers like this we initially test for bio-toxin and also for disease," Garron said. "The disease aspect is a bit more complicated. There are a lot of different diseases these animals can carry."

Garron said the root cause of the seal deaths could be an outbreak that is targeting the young immune systems of the harbor seals. A similar outbreak occurred in 2006, when Garron said a morbillvirus infected and killed seals along the Eastern Seaboard. The virus, which is known to cause distemper in animals, has been linked to a handful of die-off events involving marine mammals over the years.

Garron said the only difference is that the virus outbreak was spread out over a period of time. "This even is pretty unique in that we're seeing this large spike in a short period of time," she said.

But despite her theories on what could be the cause of what is now being considered an event, Garron said more testing must be done. "We're still not sure what's going on," she said.

The process of investigating the seal deaths involves sharing input with state officials from Maine, New Hampshire and Massachusetts. Garron said coordination is key.

A study is ongoing at Woods Hole Oceanographic Institution in Massachusetts involving whether algae blooms are playing a role in the seal deaths. Researchers at the University of New Hampshire are also playing a role in the investigation.

Inga Sidor, a senior veterinarian pathologist at the New Hampshire Veterinarian Diagnostic Lab and assistant clinical professor at UNH's Department of Molecular, Cellular and Biomedical Sciences, said she has been following the event over the past few weeks. Sidor said the fact that not only seals, but whales, tuna and even birds, are being found dead along the shoreline is troublesome. "When you start to have more than one specific group that is affected, that is when the bell starts to go off," she said.

Sidor said she is primarily involved due to the massive amount of birds — namely seagulls — being found on beaches.

Having examined birds found this past week in Rye, Sidor said she is looking into the stomach contents of the dead birds and is conducting a toxin analysis similar to the tests being done on seals and whales. The birds examined had fish in their stomachs, which Sidor said means they were eating before they died.

Their tissue samples will be examined for any signs of disease, trauma, infections or non-infectious information that could shed more light on potential causes.

From her examinations, Sidor said "oiling" is less likely, as is human interaction such as entanglement. Apart from that, Sidor said, "it's wide open." Sidor said she does, however, have a working hypothesis as to why these animals are dying off the coast.

"When you start to look at birds, and seals and cetaceans, algae blooms comes immediately to mind," she said. More data would be needed to confirm that, she said.

Tony LaCasse, a spokesman for the New England Aquarium, said the unique aspect of the event is that most of the seals found are considered to be the "young of the year."

LaCasse said preliminary results of necropsies conducted on the seals have come in but biologists aren't releasing the information until all tests are complete.

LaCasse said biologists have sent samples of tissue, blubber, muscles and almost every organ in the seals for testing. Once those results are known, LaCasse said more specific testing for viruses or bacteria could be ordered, which would make finding the reasons behind the increased seal deaths a lengthy process.

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